Microtome knife sharpener



July 3, 1962 H. l.. ETTMAN 3,041,790

MICROTOME KNIFE SHARPENER Filed sept. 14, 1959 INVENToR. HENRY l..ETTMAN Bydrkw ATTORNEY Patented .lnly 3, 1962 @tl/1,798 MECRQTBQE KNEESHARPENER Henry L. Ettman, 6348 Wydown Blvd., Clayton, Mo. Filed 14,1959, Ser., No. 839,754 2 Claims. (Cl. 51-192) This invention relates ingeneral to sharpeners, and, more particularly, to a microtome knifeSharpener.

Heretofore, various types of generally conventional Sharpeners have beenutilized for the purpose of sharpening microtome knives, such asutilized in hospitals, laboratories, and clinics, for sectioning ofprepared tissue and other materials for diagnostic and analyticalpurposes. However, none of these sharpening devices have proved inactual practice to operate in a highly eilicient manner to produce aneven, sharpened edge on the microtome knife so that any area of theknife edge will cut uniformly. All such sharpening devices currentlyused require that the wheel be constantly subjected to a cooling agent,primarily water, for dissipation of the heat developed by the frictionof the knife upon the sharpening wheel and to disperse the suspendedabrasives. The application of the coolant is accomplished by mounting ofthe wheel within a vessel containing such coolant, as Water, so that aportion of the wheel is constantly irnmersed therein. Because of thecontinuous subjection of the wheel to the coolant, it has beensubstantially impossible to maintain an even coating of abrasive thereonso that the knife is brought into direct contact with the wheelperiphery resulting, in some instances, in severe damage to the edge,and in many cases rendering the same unusable. Another type consists ofa flat glass disc on which water is dripped and acts as a coolant anddispersing medium for abrasive powders. With this type, the disc rotatesabout a vertical axis and the knife edge is presented to the wheel facerather than the periphery. An unsatisfactory elort to overcome thismarked defect has been attempted, and that is the practice of suspendingthe abrasives in the cooling agent within which the wheel rotates, sothat the latter will tend to pick up `abrasives upon each rotation. Butthis method has proved unreliable, and, at best, has caused thesharpening operations to require considerable periods of time.Furthermore, the use of such free flowing coolant-s, as water,customarily results in splashingand splattering of the water andsuspended abrasive, which condition is wholly undesirable within ascientific laboratory. Additionally, sharpening wheels as made primarilyfrom glass and stone inherently develop or contain certain surfacedefects, pits, or irregularities, wherein particles of the abrasive tendto become permanently iixed so that the sharpening wheels never attain atruly clean state whereby upon application of further abrasives alaminating or piling-up effect is caused in those portions, therebyconducing to the unevenness of the abrasive coating, and further,preventing uniformity of abrasive size, since the adhering particles maybe of different mesh than the later applied abrasives, and with thewearing-away of the latter the former will be exposed and, hence,operate simultaneously with the surrounding particles, which conditionis productive of uneven sharpening.

Therefore, it is an object of the present invention to provide amicrotorne knife sharpening device which does not require the constantapplication of an extraneous, free-flowing cooling agent, and whichdevice is so constructed as to eect high heat-conductivity for reliabledissipation of heat developed during operation.

lt is a further object of the present invention to provide a microtomeknife Sharpener which incorporates a highly polished, circumferential,operating face, which permits of even distribution thereon of anabrasive and which may be readily and entirely cleaned for receivingadditional, removable abrasive coatings which thereby present a uniformlayer at all times to the knife.

It is a further object of the present invention to provide a microtomeknife Sharpener which is highly efficient in operation, being capable ofeffecting the sharpening operation in minimum time; which may be easilyoperated and does not cause splattering or splashing; which is durablein operation; and which may be most economically produced.

These and other detailed objects are obtained by the structuresillustrated in the accompanying drawing, in

which- FlGURE 1 is a perspective view of a microtome knife Sharpenerconstructed in accordance with and embodying the present invention.

FGURE 2 is a vertical transverse section taken on the line 2-2 of FIGURE1.

FIGURE 3 is a vertical transverse section taken on the line 3 3 ofFIGURE l.

FlGURE 4 is an enlarged detail illustrating the contact between thewheel and the knife to be sharpened thereby.

Referring now by reference characters to the drawing, A designates amiorotome knife Sharpener incorporating a rectangular housing 1 havingend walls 2, 2', side walls 3, 3', a bottom wall 4, and being open inits upper portion as at S except for an inturned marginal flange 6.Extending through threaded openings in llange 6 at the corners ofhousing 1 are screws 7, the upper ends thereof passing through alignedopenings in a top closure plate 8, and being engaged by cap nuts 7.Provided upon each screw 7 between ange 6 and plate is an adjustingcollar 9, upon selected operation of which the disposition of top plate8 with respect to housing 1 may be altered for purposes presentlyappearing. Thus, for example, collars 9 on an adjacent pair of screws 7may be adjusted relatively to the remaining collars so as to cause thetop plate to be horizontally inclined, or, manifestly, all collars 9 maybe regulated for raising or lowering of said plate 8 within the rangeprovided by the available length of screw 7.

Presented within housing 1 is a prime mover or motor M secured upon amounting lil whichis supported on a bracket 11, bolted to base plate 12extending transversely between the lower inturned edges of walls 3, 3.Motor M is connected to a source of power external of housing 1 as byleads indicated at 13; there being an operating switch 14 connected tomotor M and positioned for convenient presentation of its toggle armVupon the outer surface of end wall 2. Motor M comprises a drive shaft15 having mounted, as by spaced collars c, on its outer end a balancedwheel 16, constructed of aluminum or other materials, to be discussedbelow more fully, the upper portion of which extends upwardly throughthe open, upper end 5 of housing 1 and through a slot-like opening 17formed in closure plate 8; said opening 17 being slightly greater thanthe thickness of wheel 16.

Secured or otherwise fixed on the upper surface of closure plate 8 is apair of spaced apart guide members 18, 1S' cooperating to form a way fora slide 19 which is centrally slotted, as at 20, for extensiontherethrough of a screw 21 rigid in plate 8 and having a retaining wingnut 22 threaded on its upper projecting end so that upon loosening ofwing nut 22 slide 19 is freed for movement relatively between members18, 18 and upon tightening of said nut 22 said slide 19 will bemaintained in selected position.' Guide members 18, 18 are presented soas to dene the path of movement of slide 1g along an axis substantiallytangentially aligned with, or parallel to the tangent of, the upperportion of wheel 16 extending through opening 17.

Mounted on the end of slide 1S, perpendicular thereto, and proximatewheel 16, is an elongated microtome knife holder 23 extending almostfrom end to end of closure plate 8. Said holder 23 is of a lgenerallystepped configuration having a lower step or knife support ledge 24planarwise parallel to closure plate 8, and a riser-like abutment 2S. Asthe thickness of wheel 16 is less than the length of microtome knives tobe serviced by machine A, a microtome knife must, perforce, be moved bythe operator along support ledge 24 for presenting the entire edgeportion of the knife to wheel 16. In the drawing, K indicates amicrotome knife being provided with the conventional back 26 which maybe retained upon the knife during sharpening.

Indented or otherwise inscribed upon the upper surface of closure plateS spaced from knife holder Z3 and axially parallel therewith is a guideline 27 so related to sharpening wheel 16 as to be aligned with theremote terminus of the at curve (to be described) at the extremeprojecting portion thereof. Thus, knife holder Z3 will be adjustedlydisposed so that the edge of a knife to be sharpened, and supportedthereon, will be in alignment with guide line 27 by which conditionproper address of the knife K to wheel 16 is certain.

Provided circumferentially about the entire peripheral surface of wheel16 is a Wheel facing or cover 28 fabricated of relatively thinsheet-forming material, of uni` form thickness, being secured to thewheel in any suitable manner, and having its exterior, knife-confrontingface, highly polished to a mirror or near mirror finish for presenting aconsistently smooth surface, free of any surface defects orirregularities, and having thus a minimum coefficient .of friction. Themost important property of wheel 16 together with its facing or cover 28is that the same have a high heat conductivity for heat-exchange orthermal conductivity, depending upon the unit of measurement for theparticular material. Thus, for the purposes of the present invention ithas been found that wheels constructed of the following materials havethe desired characteristics: aluminum or aluminum alloy, such as analloy comprising 98.9% aluminum, .4% silica, and .7% magnesium (with ahardness of approximately 73 Brinell scale), or of copper, or copperalloys; hard woods, such as, mahogany, maple, oak; and plastics, suchas, phenol-formaldehydes, phenol-furfurals, thermosetting resin-rubbercompounds, melamine formaldehydes, various phenolic plastics,tetraiiuoroethylenes, and polypropylenes. The facings or covers 28 maybe of the same material as that of the wheel or may be constructed fromany otherl of the above specified materials. It is not requisite thatwheel 16 and its cover 2S be formed from the same material. Thus, awheel 16 fabricated of aluminum could have applied thereon a facing 28formed of copper, wood, gold, plastic, etc. AIt is critical that thefacings or covers 28 of the wheel 16 have the capability of providing ahighly polished surface or mirror finish for purposes presentlyappearing, and that such facings together with the wheels further havethe property of high heat or thermal conductivity. With respect tomaterials of construction for facing or cover 28, it as been founddesirable that those of metallic character have a heat of conductivitywithin the range of A510-1.0. Thus, within this range will be found castaluminum, alloys thereof, copper, alloys thereof, pure gold, and alloysthereof. With respect to other materials which are measured in terms ofthermal conductivity, such as, the hardwoods and the plastics, suchshould have a thermal conductivity within the range of .3 to 1.3, andthis would include mahogany, maple, oak, and the plastic materials, asabove stated. In passing, it should be recognized that wheel 16 might beformed Without a facing or covering 28 such as being made entirely ofwood, or the like, but in any event must possess the capability ofproviding a mirror finish and having a minimum thermal conductivity of.3 or a l minimum heat conductivity of .4, and a Brinell hardness withinthe range of 50 to 250.

In the sharpening of microtome knives it is vital that the cutting edgeportion thereof be disposed flatwise upon the Wheel in order to attainsubstantial uniformity in such edge. Without such flat presentation, theresulting edge will be irregular and hence inadequate in cuttingsections of uniform thickness, and obviously unfit for providing that`degree of thinness in sections so vital for innumerable analyses. Ithas been found that a wheel having a diameter of at least eight incheswill provide in its circum ference a curve of such angle as to besubstantially coincident in extent with the edge portion of microtomeknives and substantially coincident with its chord so as to provide whatmight be termed a flat curve, and thereby assure the critical engagementwith the knife over the necessary surface thereof for attaining therequisite sharpened edge. Consequently, it is the combined diameter ofwheel 16 and facing 2S which will control in this instance. Thus, FIGURE4 of the drawing illustrates this contact between the facing 28 of wheel16 and the edge of knife K.

The angle of the bevel of the cutting edge on knife K may through theoperation of machine A be of any desired degree, with the relationshipbetween closure plate 8 and wheel 16 being determinative, as by theselected positioning of closure plate 8 through operation of collars 9.Thus, as closure plate 8, together with knife holder 23 thereon, isrelatively raised, a reduced portion of Wheel 16 will projectthereabove, through opening 17, so that a somewhat steep bevel may beobtained, While conversely upon lowering of closure plate 8 a relativelyshallow bevel will result. But, regardless of such adjusting thellatwise engagement between Wheel 16 and knife K will be maintained. Itwill be observed that the adjustability of knife holder 23 throughoperation of slide 19 will permit machine A to accommodate microtomeknives of varying sizes.

Ther sharpening operation is easily accomplished by use of machine A, asthe user after having adjusted knife holder 23 with respect to guideline 27 for the particular knife being serviced, and positioned closureplate 8 for the desired degree of bevel, need only slide knife K alongstep 24 -so as to present one surface of the edge portion to Wheel 16,and then to turn knife K over to present the opposite surface of thecutting edge for sharpening.

Thus, with the outer face of covering 23 being ground and polished to amirror or new mirror finish for presenting a smooth, even surface, andwheel 16 being rotated in a direction away from knife K, as indicated bythe arrow in FIGURE 4, abrasives of multi-faceted crystalline character,such as, aluminum oxide, diamond dust, or the Said abrasives like, arethen applied on said covering. are preferably maintained or suspended ina stick of a waxy-like well-known carrier or vehicle, so that the stickend is thus rubbed across the rotating cover for applying a coating ofthe abrasive; which latter for use with the present device should have aminimum hardness of 8 or more Moh scale, and with a micron size withinthe range of .5 to 8. Understandably, the liner the abrasive, thegreater should be the speed or rotation of wheel 16 which is adapted foroperation between 1250 and i() revolutions per minute. It is recognizedthat variable speed controls (not shown) may be provided with motor M soas to allow for selection of the speed of rotation indicated by the sizeof the abrasives between the stated limits. By lightly applying theabrasives to the Wheel cover 28 in the manner stated, a coating will bedeveloped which is thereon subjected to a non-aqueous dispersing agentas contained within an absorbent pad, which latter is manually movedcontactingly about the abrasive coat ing for assuring uniformity ofthickness and evenness of distribution thereof. The abrasive coating onthe Wheel then takes on the character of a relatively thin paste-likelayer, having the desired viscosity for adherence to the Wheel surfaceand for promoting desired sharpening results. The dispersing agent isdesirably a low-volatile liquid, as selected from combinations of range,distillate, and residual oils, glycols, and glycol derivatives, bothwith and Without wetting agents, all of which are Well known in the art.The abrasive coating will thus be evenly distributed so that at alltimes the microtome knife being sharpened will maintain contact with theabrasives and, hence, not be brought into friction-producing, damagingcontact with the bare face of cover 28 through any abrasive-barrenzones. Such heat as may be generated through the engagement betweenknife K and the abrasives Will readily be dissipated through theinherent properties of the materials of construction of Wheel 16 andcover 28 as shown hereabove, and, accordingly, no extraneous coolingagent need be applied during the sharpening action.

Thus, by obviating the use of a free-owing liquid cooling agent, thepresent invention assures an even distribution of abrasives, avoidanceof splattering, and with the sharpening action being eifected in areliable and relatively rapid manner, no longer necessitating theservices of a highly skilled operator. -In actual practice, it has beenfound that at least three microtome knives may be sharpened before' anyadditional application of abrasives is required. So, considerableeconomy in time may be elfected through the usage of the presentinvention.

The utilization of the mirrored-surface cover or jacket 28 prevents thepermanent adherence thereto of any abrasives so that all such appliedabrasives are readily removable after sharpening operation, as by theexercise of simple, conventional cleansing actions whereby the coversurface is returned to its clear, polished state. A new abrasive maythus be used for each ofsucceeding operations without danger of anyundesirable mixture or union with a lpreviously applied abrasive. Withthe sharpening wheels heretofore used, such as, of iron, glass, stone,and the like, the surface-cleaning operations were never capable ofentirely freeing the peripheral surface of such Wheels of previouslyapplied abrasives due to the pitting and other irregularitiesconsistently found in such wheels. So the subsequently applied abrasiveswould consistently and necessarily be intermingled with other,previously applied abrasives, so that the sharpening results Would beindefinite and unreliable. Furthermore, the adherence of previouslyapplied layers of abrasives would reduce materially any heat transfercapabilities of the grinding Wheels so the knife being sharpened Wouldbe subjected to a relatively marked increase in heat with its attendantundesirable results.

"Thus, as shown hereinabove, the present device presents a Wholly newand completely effective departure from previously known structures inproviding a mirrored surface to a sharpening wheel for microtome kniveswhich will permit the irm adherence thereon of vsuitable abrasives andyet allow the same to be entirely removed subsequent to operation. Thepresent device does not require the utilization of any cooling agent andhence is competent to operate for longer periods and in a highlyellicient manner. Furthermore, the present invention may be mosteconomically' produced; is operated at extremely low cost, and in thisday of scarcity of highly skilled technicians, does not require theservices of such type individuals, but may be used by individuals aftermost limited instruction.

It should be understood that changes and modiiications in the formation,construction, arrangement, and combination of the several parts of themicrotome `knife Sharpener may be made and substituted for those hereinshown and described Without departing from the nature and principle ofmy invention.

Having thus described my invention, what lT claim and desire to secureby Letters Patent is:

1. A machine for sharpening microtome knives comprising a easing, aWheel provided in said casing, said Wheel having a peripheral face,means for eecting rotation of said wheel, microtome knife guide andsupport means provided on said casing for presentation to the peripheralface of said Wheel of the edge of a microtome knife to be sharpened,said wheel rotation means being adapted to rotate the Wheel in adirection away from the edge of a presented knife, a continuous facingmember of uniform thickness mounted on the peripheral face of said wheeland being co-extensive therewith and being completely supported thereby,said Wheel and said facing member being each constructed of materialhaving substantially high heat conductivity so as to adapt the saidmachine during usage for rapid thermal transfer and to render saidmachine thereby independent of extrinsic cooling means; said facingmember being resistant to pitting and development of surfaceirregularities, the outer surface of said facing member being polishedto a substantially mirror inish for providing adhesive characteristicsfor repeated accommodation thereon of various size abrasives without pitformation.

2. A machine for sharpening microtome knives as defined in claim 1 andfurther characterized by the Wheel being constructed of material havinga minimum heat conductivity of .4 and a Brinell hardness Within. therange of 50 to 250, and the facing member being constructed of materialhaving a heat conductivity within th-e range of .45 to 1.

References Cited in the file of this patent UNTTED STATES PATENTS EttmanDec. 8, 1959

